Changing pattern of primary hyperoxaluria in Switzerland

Background. The clinical course of primary hyperoxaluria (PH) is greatly variable and diagnosis is often delayed. Little is known about the overall occurrence and current prognosis. Methods. We evaluated all known patients with PH residing and observed in Switzerland during the last 15 years with the help of a survey among Swiss nephrologists. Results. Of the 25 patients observed between 7/79 and 6/94 in Switzerland, 18 were alive in 1994-14 on conservative therapy and four on renal replacement therapy (RRT). Twenty-two patients had PH type 1 ; the exact type was not determined in three. The estimated prevalence of PH (type 1) is 2 per million population; the minimal incidence is 1 per 100 000 live births. Diagnosis was delayed by 8 years (median) except in infants. Five patients were pyridoxine sensitive. According to life table analysis, 20% of patients were in end-stage renal failure (ESRF) and 10% had died by the age of 15 years, and 50% were in ESRF and 20% dead at 25 years. Prognosis has improved : Five of 13 patients died during the first half of the observation period as opposed to two of 20 in the second part. Conclusions. Overall prognosis appears better than hitherto believed considering the large clinical spectrum of PH. Greater awareness of PH is needed to improve further long-term prognosis.